Activity of the phenolic pathway’s enzymes influenced by resistance-inducing chemicals in tomato plant

Abstract

Chemical elicitors, namely salicylic acid (SA), β-amino butyric acid (BABA), chitosan (CHT) and 2,6-dicholoroisonicotinic acid (INA), are known to play a role in the induction of plant resistance to pathogens by increasing the activity of enzymes of phenolic synthesis pathways such as peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase. These chemical elicitors applied to tomato as an 8 h seed treatment, 2 h seedling treatment and seed plus seedling treatment increased the activity of peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase. The highest increase in peroxidase and phenyl alanine ammonia lyase activity was induced by the seed plus seedling treatment with 15 mM β-amino butyric acid. The increase in these enzyme activities was 70.5% and 39.3% higher, respectively, over control, whereas the highest increase in polyphenol oxidase activity was induced by the seed plus seedling treatment with 1.5 mM salicylic acid. Polyphenol oxidase activity increased 137.9% compared to the non-treated control. Similarly, seed treatment as well as seedling treatment with the elicitors particularly salicylic acid, β-amino butyric acid and chitosan elicited increased activity of peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase of the phenolic syntheses pathways, which are known to be the basic components of the resistance induction mechanism.